I am trying to combine two stl images

I am trying to combine two stl images. I want to do a Boolean operation to add a fan mount to a cover for a 3d printer electronics cover.


I don’t use it much but,
MeshBooleanUnion seems to be used to combine stls.


  1. MeshtoNURBS to change to polysurface,
  2. then booleanunion
    should combine the stl.
    then export out to stl again.

Read this BEFORE you use MeshToNURB:

If you can not merge with Rhino 2 mesh files that are closed, I recommend using a “more suitable” program to this kind of thing. They are “competition” programs (no Mcneel rancor) Meshmixer and Geomagic are the ideal candidates.

Why do you need to combine them? Just create or import both meshes in Rhino, position them as you need it, then export all as one .stl file. 3D printing software like Cura will treat it as one ‘booleaned’ print object.


@John_Anderson Of course you do. If there are no modeling needs is the best and easiest way. However, it is a road that can cause problems of printing failure.
Personally I never print .stl files that intersect. (Holes or gaps inherent risks)